Combine coconut milk, sugar, and pandan leaves in a small saucepan. Bring to a simmer over medium low heat. Stir to dissolve sugar. Turn off stove and allow coconut milk mixture to cool.
Grease or line a loaf pan with banana leaf. Preheat oven to 190�C.
In a large bowl, combine grated tapioca, eggs, and melted butter. Pour in coconut milk mixture. Stir to incorporate all the ingredients.
Pour mixture into prepared pan. Bake for 1 hour 30 minutes or until the top is a light golden brown color. Remove and allow cake to cool before cutting and serving.